If you look outside, you probably will see some kind of insect. If your first instinct is to kill it, take a moment to think about all of the benefits insects provide to the environment.

  Entomologists, scientists who study insects, estimate that there are more than 800,000 species of insects found throughout the world. Only a few hundred of these insects are considered harmful. Mosquitoes, for example, are considered harmful. They bite humans and other animals, and their bites can cause skin pain and spread disease. Desert locusts also are considered harmful because they destroy crops causing billions of dollars in damage each year.

  However, the number of helpful insect species far outweighs the number of harmful species. Some insects make up a vital part of the food chain. Many different birds, reptiles, fish and even plants eat insects. There are also about 500 insects that people in various parts of the world eat. These insects are considered delicious food and prized for their high protein, mineral, and vitamin content. Other insects produce valuable commercial products such as silk, wax, and honey.

  Of all the insects, perhaps the most important are those that travel from flower to flower and pollinate(授粉) the plants they visit. Agriculture around the world would be very different without the bees, butterflies, moths, flies and wasps that pollinate many crops. In fact, nearly one-third of the food you eat depends on plants that are pollinated by insects!

  While it is true that some species of insects harm or annoy us, you should not automatically reach for the bug spray when you come across an insect. You may be destroying one of the hundreds of thousands of insects that provides many benefits to human beings.

D

    Scientists are trying to make the deserts into good land again. They want to bring water to the deserts，so people can live and grow food. They are learning a lot about the deserts. But more and more of the earth is becoming deserts all the time. Scientists may not be able to change the deserts. Scientists think that people make deserts. People are doing bad things to the earth.

    Some places on the earth don't get much rain. But they still don't become desert. This is because some green plants are growing there. Small green plants and grass are very helpful to dry places. Plants don't let the hot sun make the earth even drier. Plants don't let the wind blow the earth away. When a little bit of rain falls，the plants hold the water. Without the plants，the land can become a desert much more easily.

   B

     Many people have long dreamed of being able to fly around as simply as riding a bicycle.  Yetthe safety and strength of a flying bike was always a big problem.Over the past 10 years, developments in technology have moved the dream of personal flying vehicles closer to reality. Now, two groups of inventors say such vehicles may be available very soon.

      Grant Stapleton from Malloy Aeronautics says the Hoverbike, which is able to get in and out of small spaces very quickly, will be a truly personal flying vehicle.  "It can be moved across continents very quickly because it can be folded and packed," he adds.

      Mr. Stapleton says safety was the company's main concern when developing the Hoverbike. He ays the designers solved the safety issue by using overlapping rotors  (折叠旋翼)  to power the vehicle. The company is testing both a one-third size model and a full-size prototype  (原型)  of the Hoverbike.

     Inventors say their Hoverbike will most likely be used first by the police and emergency rescue teams.

     In New Zealand,  the Martin Aircraft Company is also testing a full-size prototype of its personal flying bike, called Jetpack. It can fly for more than 30 minutes, up t0 1,000 meters high and reach a speed of 74 kilometers per hour.

     Peter Coker is the CEO of Martin Aircraft Company.  He said Jetpack "is built around safety from the start, " In his words, "reliability is the most important part of it.  We have safety built into the actual structure itself, very similar to a Formula One racing car. "

     Jetpack uses a gasoline-powered engine that produces two powerful jet streams.  Mr. Coker says it also has a parachute (降落伞) that can be used should there be an emergency. "It opens at a very low altitude and actually saves both the aircraft and the pilot in an

emergency," he adds.

It has often been suggested that the ocean, rather than space, is the true final frontier. From the extremely high pressure that threatens human lives to unknown geography that can injure people and machines alike, various things make sending human explorers hazardous. The deepest section of the ocean is the Marianas Trench, which begins at 20,000 feet. It has points where the depth approaches seven miles and the pressure reaches eight tons per square inch. That’s why the Marianas Trench remains largely unexplored to this day.

Even knowing about all of the difficulties, however, some scientists feel the draw of the ocean’s depths. The environment, unfriendly though it may be to man, is friendly to others, allowing for the development of quite a few creatures not found anywhere else on the planet. The first exploration of the Marianas Trench’s floor took place in 1960. Since then, the cost of sending people back has been seen as too great.

The goal, then, has been to find a way to learn about this frontier without risking the lives of explorers. One way that scientists have discovered new information is through the use of sonar. As sonar technology — a sound-based method of determining surroundings — has improved, scientists have been able to get more accurate maps of the ocean’s floor.

Another method of exploration that has become more common in recent years is to use machines that have no people working inside them. These include underwater cameras and robots. The latter have become increasingly common in recent years.

Although most of the robots used so far have been attached to a larger device with people aboard, the day when the robots can move independently may not be far off. As technology is being advanced, it seems quite likely that automatic robots will become more competent ocean floor explorers than humans.

 We live in a digital world now, and a student’s  technology needs have changed. For the early years, say when you are in primary school, you can get by with no technology at all. Even if you have a computer, it’s a good idea to get familiar with libraries.

As you get closer to middle school, a computer with Internet access becomes more of a necessity. Teachers will often give assignments that require a student to use the Internet for research. After a computer, technology choices for students become more difficult to make － especially when it comes to cellphones. Kids will beg their parents for cellphones, especially in middle school. For many parents, it’s a safety issue: they want to know that their kids can reach them quickly if necessary. For teachers, cellphones can be used to record lessons when students are absent. But many teachers dislike cellphones. Some kids send messages or have talks in the class. Sending messages also raises the problem of cheating on exams. More and more schools are now forbidding the use of cellphones.

Many kids see iPods as necessary things to have. IPods are great for music, but do they do anything good for your children’s education? Maybe they do.That is the opinion of Doug Johnson, an educator for 30 years. Johnson says that educators should accept all new forms of technology in the classroom, including iPods. “Some do more with  their cellphones  than we can do with our laptops，” he jokes. “I don’t think we should be afraid. The truth is that it’s easier to change the way we teach than to change the technology habits of an entire generation.”

B

Can dogs and cats live in perfect harmony in the same home? People who are thinking about adopting a dog as a friend for their cats are worried that they will fight. A recent research has found a new recipe of success. According to the study, if the cat is adopted before the dog, and if they are introduced when still young (less than 6 months for cats, a year for dogs), it is highly probable that the two pets will get along swimmingly. Two­thirds of the homes interviewed reported a positive relationship between their cat and dog.

However, it wasnˈt all sweetness and light. There was a reported coldness between the cat and dog in 25% of the homes, while aggression and fighting were observed in 10% of the homes. One reason for this is probably that some of their body signals were just opposite. For example, when a cat turns its head away it signals aggression, while a dog doing the same signals submission.

In homes with cats and dogs living peacefully, researchers observed a surprising behavior. They are learning how to talk each otherˈs language. It is a surprise that cats can learn how to talk “dog”，and dogs can learn how to talk “cat”．

Whatˈs interesting is that both cats and dogs have appeared to develop their intelligence. They can learn to read each otherˈs body signals, suggesting that the two may have more in common than we previously suspected. Once familiar with each otherˈs presence and body language, cats and dogs can play together, greet each other nose to nose, and enjoy sleeping together on the sofa. They can easily share the same water bowl and in some cases groom (梳理) each other.

The significance of this research on cats and dogs may go beyond pets—to people who donˈt get along, including neighbors, colleagues at work, and even world superpowers.  If cats and dogs can learn to get along, surely people have a good chance.

C

Nearly one billion of the world’s people do not have an“adequate (足够的)”supply of water, and most of these people are in the world’s developing nations. The lack of water services is the cause of much disease and illness in the developing nations. Increased demand and greater use of water (caused by population increases) often create the need for extra water treatment because water from new source areas tends to be of lower quality. Water services would be improved if the construction of facilities (设施) were not so costly.

      Water pollution in the developing nations is sometimes caused by overuse of fertilizers and a general lack of pollution prevention laws. Access to good wastewater treatment facilities in these countries is very limited. As a result, water bodies in the developing nations are often open to human and animal waste products. Besides, the waste chemicals of factories are also poured into these water bodies.

       In the developing nations, floods account for about 40 percent of all deaths caused by natural disasters. For example, 3.7 million people were killed in a 1931 flood on China’s Yangtze River. However, floods also carry sediment（沉积物）and nutrients into flood plains. This natural process is important for agricultural production. Programs for flood management should consider and find a way to balance the harmful and beneficial aspects of floods.

      Throughout the developing countries, deforestation (滥伐森林) is being caused by a combination of overpopulation, improper land use practices, and a lack of environmental laws. Soil erosion (侵蚀) is a natural process, but deforestation and other human activities have led to a five times increase in the average levels of sediment carried in the world’s rivers. Too much sediment in rivers can damage ecosystems and fisheries, affecting the people who directly depend on them.

The expression "a thirst for knowledge" may soon have a new meaning for millions of people who have no way to get clean water. Researchers have developed a book with specially treated pages that can turn dirty water into clean and drinkable water. They say their invention could improve the lives of many in the developing world.

    About 700 million people around the world are at risk of disease or even death because their drinking water is not clean. The water is polluted by harmful bacteria.

    The book contains 25 pages. Each page is about one millimeter thick. The pages contain very small particles(微粒)of silver. The pages can be used as filers(过滤器)to remove harmful microorganisms(微生物)that can pollute drinking water. The filter kills the organisms that pass through it.

    Pictures on the pages show the dangers of dirty water and how to use the book for those unable to read. The pages are made of filter paper. They are designed to be torn from the book. Water can be poured through the paper to be cleaned.

    Ms Dankovich, the inventor, sys each page can treat up to 100 liters of water. She recently presented her invention at the meeting of the American Chemical Society in Boston, Massachusetts. She was asked whether she had considered adding classic literature on the bookˈs pages.

    "The idea pf classic texts—thatˈs of interest maybe later. We have discussed a little bit more exciting text. But we really havenˈt had the time to go through that part," she says.

    Teri Dankovich and another researcher tested the drinkable book in Bangladesh, Ghana and South Africa. The tests proved to be successful.

    Water for Life, a non-governmental organization, has provided financial support for the project.